Beverage dispenser

Abstract

A beverage dispenser for dispensing a post-mix beverage is characterized by a disposable concentrate beverage unit and a disposable pump unit that are housed in a refrigerated area of the beverage dispenser. The pump unit is operable to dispense metered volumes of concentrate for mixing with a regulated flow of diluent to dispense a required ratiometric mixture thereof.

1 . A beverage dispenser for dispensing a post-mix beverage from a disposable concentrate pump unit comprising two inlet valves, two pump chambers having a flexible membrane and two outlet valves, the dispenser comprising:
 a diluent supply system to supply a flow of diluent to a section of the disposable pump unit;   a cabinet area for receiving at least one reservoir of concentrate; and   at least one pumping station for receiving, retaining and actuating a disposable pump unit, wherein said pumping station comprises:   a drive plunger associated with each pump chamber and arranged for reciprocal movement to displace the flexible membrane in a first direction to expel concentrate from the pump chambers and in a second direction to draw concentrate into the pump chambers; and   vacuum means for applying a pressure differential across the flexible membrane when a drive plunger is moving in its second direction so as to cause concentrate to be drawn into the pump cavity as a drive plunger is withdrawn.   
   
   
       2 . A beverage dispenser according to  claim 1 , wherein each drive plunger is driven by a cam. 
   
   
       3 . A beverage dispenser according to  claim 2 , wherein the cams are profiled such that the movement of a drive plunger in the second direction is faster than movement of the plunger in the first direction resulting in concentrate being drawn into the pump chamber in a shorter time interval than it is expelled therefrom. 
   
   
       4 . A beverage dispenser according to  claim 1 , wherein each pump chamber has a dedicated vacuum means and a conduit leading from said dedicated vacuum means to an outer side of the flexible membrane, the disposable concentrate pump sealingly engaging with the pumping station so as to form an enclosed area between each pump chamber and the pumping station. 
   
   
       5 . A beverage dispenser according to  claim 4 , wherein each vacuum means comprises:
 an enclosed chamber having an inlet check valve and an outlet check valve, the inlet check valve being in the conduit between the vacuum means and the outer side of the flexible membrane; and   a vacuum drive member movable in said enclosed chamber in a first direction to draw air through the inlet check valve and in the other direction to expel air from the enclosed chamber via the outlet check valve, thereby creating a pressure differential across the flexible membrane.   
   
   
       6 . A beverage dispenser according to  claim 4 , wherein each conduit passes into and through a plunger and terminates at an opening in the end of the plunger which, in use, displaces the flexible membrane. 
   
   
       7 . A beverage dispenser according to  claim 5 , wherein each vacuum drive member is driven by a cam. 
   
   
       8 . A beverage dispenser according to  claim 7 , wherein each vacuum drive member cam and drive plunger cam, for each pump chamber, are driven by an associated common drive shaft. 
   
   
       9 . A beverage dispenser according to  claim 8 , wherein the drive shafts for the pump chambers are driven simultaneously by a single motor. 
   
   
       10 . A beverage dispenser according  claim 1 , wherein each of the concentrate pump inlet valves comprises a flexible membrane overlaying an inlet orifice and the pumping station further comprises an inlet valve plunger associated with each inlet orifice and arranged for reciprocal movement to displace the flexible membrane in a first direction to cover and close the inlet orifice thereby preventing flow of concentrate therethrough, and in a second direction to allow the membrane to move away from the orifice and allow concentrate to pass therethrough. 
   
   
       11 . A beverage dispenser according to  claim 10 , wherein each inlet valve plunger is driven by the common drive shaft by means of a cam. 
   
   
       12 . A beverage dispenser according to  claim 1 , wherein each of the concentrate pump outlet valves comprises a flexible membrane overlaying an outlet orifice and the pumping station further comprises an outlet valve plunger associated with each outlet orifice and arranged for reciprocal movement to displace the flexible membrane in a first direction to cover and close the outlet orifice thereby preventing flow of concentrate therethrough, and in a second direction to allow the membrane to move away from the orifice and allow concentrate to pass therethrough. 
   
   
       13 . A beverage dispenser according to  claim 12 , wherein each outlet valve plunger is driven by the common drive shaft by means of a cam. 
   
   
       14 . A beverage dispenser according to  claim 11 , wherein each cam is profiled to open the valve quickly, to maintain the valve in its open position as the pump chamber fills, and to then close the valve quickly. 
   
   
       15 . A beverage dispenser according to  claim 13 , wherein each cam is profiled to open the valve quickly, to maintain the valve in its open position as the pump chamber fills, and to then close the valve quickly. 
   
   
       16 . A beverage dispenser according to  claim 1 , wherein each outlet valve is a check valve. 
   
   
       17 . A beverage dispenser according to  claim 1 , wherein the pumping station actuates the sets of inlet valves, pump chambers and outlet valves out of phase with each other. 
   
   
       18 . A beverage dispenser according to  claim 3 , wherein the flows of concentrate expelled from the pump chambers overlap one another so that, in operation of the pump unit, concentrate is continuously expelled from the pump. 
   
   
       19 . A beverage dispenser according to  claim 1 , wherein the diluent supply system comprises a flow meter to measure the flow of diluent passing therethrough. 
   
   
       20 . A beverage dispenser according to  claim 19 , wherein the rate of pumping of concentrate is controlled dependant on the flow of diluent being supplied to the pump. 
   
   
       21 . A beverage dispenser according to  claim 20 , including motor means for operating the pump unit, the flow rate of concentrate delivered by the pump unit being dependent upon the speed of the motor, and including means for controlling the speed of the motor dependant on the measured flow of diluent. 
   
   
       22 . A beverage dispenser according to  claim 21 , wherein the flow of diluent is set to a desired flow rate. 
   
   
       23 . A beverage dispenser according to  claims 1 , including a disposable pump cartridge comprising a concentrate inlet leading to the inlet valves, each inlet valve controlling the flow of concentrate to an associated one of the pump chambers having the flexible membrane, a diluent inlet, and the outlet valves. 
   
   
       24 . A beverage dispenser according to  claim 22 , wherein the outlet valves comprise check valves allowing concentrate to flow in the direction out of the pump chambers. 
   
   
       25 . A beverage dispenser according to  claim 22 , wherein the pump cartridge comprises a static mixer downstream from the pump chamber outlet valves and the diluent inlet. 
   
   
       26 . A beverage dispenser according to  claim 25  wherein, the static mixer comprises means to maintain a back pressure on the pump chambers and diluent inlet. 
   
   
       27 . A beverage dispenser according to  claim 26 , wherein the means to maintain back pressure comprises a flow restriction at a downstream end of the static mixer. 
   
   
       28 . A beverage dispenser according to  claim 23 , wherein the diluent inlet comprises a check valve to allow diluent to flow into the cartridge but preventing flow in the opposite direction.